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No it isn’t complicated: we are monogamous

A Slate article available here discusses the question whether humans are monogamous. It’s worth reading as an example of how laughably bad evolutionary psychology can be. Instead of looking at what humans do and what most of us are most interested in, it begins by considering the human penis and wondering which ape penises the human penis resembles most.

…Which reminds me of an old philosophical joke: “My uncle was almost US President – he was skipper of PT 108!” This is funny, because during the Second World War Jack Kennedy was skipper of the patrol boat PT 109. Obviously, the proximity to 109 of the number of the patrol boat you’re the skipper of is no measure of how close you are to becoming President of the US. It assumes a mistaken dimension of similarity.

How would this sort of thinking work in biology? It might emerge in thoughts such as the following: bonobos live in the Congo, and they’re not monogamous; so the humans who live in the Congo aren’t monogamous either. Fail – where you live has nothing to do with how you normally reproduce. Nor is it any better to appeal to genetic proximity between species: species diverge because they occupy different environmental niches, adopt different strategies for reproduction, and so on. Small genetic differences often accompany large differences in lifestyle. For example, Galapagos finches are very closely related to each other, but they eat a wide variety of different foods, and thus have strikingly different ways of life. These differences were essential for their survival, and explain how they diverged in the first place. Similarly, although most non-human apes are not monogamous, some non-human apes are. The fact that we humans are a species of ape implies nothing.

The shape or size of of the human penis is probably entirely irrelevant to the question whether humans are monogamous. The human head is unusually large: that makes unusual demands on the human birth canal, and that in turn makes unusual demands on the human penis. Of course the human penis differs from that of other apes, just as our heads differ from the heads of other apes. No doubt other ape penises differ from each other, like other ape heads differ from each other.

The size of the human head actually does have some bearing on the question of human monogamy. Big brains are costly to maintain and to grow, both in terms of metabolism and learning. If humans who have healthy, well-fed brains, and skilled, knowledgeable minds do better – not just better at survival but better at getting chosen in the tricky game of sexual selection – we should expect to see whichever reproductive arrangements most effectively make them better. I think such arrangements are those of monogamy. The reproductive task of humans is in some ways similar to that of flying birds, which have to convert an egg into a flight-worthy fledgling in a very limited time “window” set by the length of the season. Their usual strategy is monogamy, with both parents involved, although of course monogamy is never perfect because cheating occurs in all monogamous species. Even where cheating occurs, successful reproduction normally makes demands on two adults rather than just one.

But the real clincher is simple observation: wherever we look, at whatever point in history, humans are and have always been intensely interested in love and marriage. Human attachment is more than an interest: it looks more like an obsession when we compare humans to most other animals such as non-monogamous apes. Love is the main theme of all forms of human art. Long-term partnerships are sought everywhere, from classified ads in newspapers to newer forms of “social media”.

The Slate article referred to above tells us that “According to anthropologists, only 1 in 6 societies enforces monogamy as a rule.” What they probably mean is that only 1 in 6 societies disallows divorce as a matter of fanatical adherence to law or scripture. But accepting that marriages often break down is different from not recognizing marriage or not acknowledging long-term partnership as an institution at all. And all human societies recognize long-term partnerships, as evolutionary biologist Helena Cronin often explains in detail.

There are several reasons why anthropologists and others overlook or seek to downplay the ubiquity of monogamy. Some of them illustrate errors that are philosophically instructive in themselves:

Like much “research” in the humanities, anthropologists’ observations are neither repeatable nor inter-subjectively verifiable, and they involve more interpretation than observations within the genuine sciences. Some anthropologists have interpreted their subject matter with such a heavy-handed political agenda or pervasive ideology that their work has become notorious. Margaret Mead’s writings about Samoa are better-known for their errors of interpretation than for what she actually got right.

The urge to say that humans are not monogamous had a resurgence with the “free love” movement of the 1960s. In this movement, a subculture of mostly young people hoped to break free from the hidebound and mostly monogamous arrangements that limited the freedom of their parents. But nearly always, the tensions and jealousies so familiar to those in monogamous arrangements re-emerged. It seems we are hard-wired to become attached to a single partner and to demand that that partner remains attached to us in return. This is an ideal, and the reality often falls short of the ideal. When it does fall short it spells trouble, but not the sort of trouble that can be avoided by ignoring or hoping to override human nature. Alas, for many years the academic establishment was populated by more elderly members of the “free love generation” who did just that.

Members of the “free love generation” weren’t the only ones to adopt an alternative lifestyle that might be expected to leave monogamy behind. Over the centuries, often out of tragic necessity, both male and female homosexuals had to join a sort of underworld of sexual activity in which legal marriage did not exist. In some places this involved unusual promiscuity, much as it did with heterosexual hippies in the 1960s. But in no place did it not involve long-term love partnerships as well. The urge to join such a partnership seems to belong to those of all sexual preference, even those who would eschew it if it really were such an “unnatural imposition” of human culture.

Nowadays, the urge to say that humans are not monogamous is often seen in two superficially opposed corners: feminism and laddism. Both seem to resent any sort of dependency between the sexes, both prefer to think that women don’t need men to help raise children, and for notably different reasons, both prefer to think that mothers shouldn’t depend on the fathers of their children for support. Because “both sides” seem to arrive at the same conclusion, it might seem to be surrounded by an air of consensus. Those who find consensus convincing should look instead at the vast majority of humans who belong to neither of these extremes, and instead agree that the involvement of two parents is the best and most “natural” arrangement for raising children, as well as for growing old in.

It is sometimes claimed that institutions like marriage are imposed on humans by human laws, as if nurture overrides human nature, which would otherwise be non-monogamous. But nurture adds detail to innate human capacities and urges rather than opposing or overriding them. Human culture such as our legal system often involves the policing of arrangements that the majority would abide by anyway, in the absence of such laws, as a matter of unforced natural choice. This is true of laws of ownership, and it is just as true of laws concerning marriage and divorce. So the fact that we have laws that seem to “enforce” monogamy – by making special allowances for it – does not detract from its naturalness. It isn’t a “social construct” or something “imposed by society” as an unnatural afterthought.

The Slate article cited above says that the question of human monogamy is “complicated”. I think they say this because they assume the concept of monogamy is perfect, like the concept of a perfect circle, and therefore simple. Their concept is too simple for the reality to match it, so the reality ends up looking more complicated than the concept. But that perfect concept is too simple. Some members of all monogamous animal species cheat, and in doing so they do not make their species as a whole any less monogamous compared with alternative reproductive arrangements. The concept of “monogamy” in the claim that “humans are monogamous” should be understood as being analogous to the concept of “round” in the claim that “the Earth is round”. We say the Earth is round because it’s shaped like a ball rather than flat. We don’t say it’s round because we think it’s a perfect sphere. Analogously, humans are monogamous because human children normally need the care and attentions of two parents rather than one, and new children are born before older children have reached adulthood. So normally the same parents are involved with each successive child. This involves a pair bond that in favorable circumstances lasts for life. It doesn’t matter much that it often doesn’t actually last for life: an animal that dies before it reaches its species’ life expectancy is no less a member of that species for dying young.

Perhaps it is because a faithful lifelong partnership is not often achieved among humans that monogamy is often treated as an ideal. But it should be understood as a moral or personal ideal rather than as a conceptual ideal like a perfect sphere. But it is also a biological reality, like “good health”. Once we grasp that all the other animals we unhesitatingly call monogamous have the same problems and shortcomings as ourselves, we see that ours too is a monogamous species. It’s simple really.

3 thoughts on “No it isn’t complicated: we are monogamous”

Two points though. The anatomical point related to correlations in primates, where penis and testes size correlate to sexual practices. If, for example, testes size does not differ due to evolutionary reasons, why /does/ it differ. This is not an evolutionary psychology question – its a pure evolutionary question.

The other point is that you are creating a dichotomy between monogamy and…well, everything else (polygamy, promiscuity, serial promiscuity…) There are varying degrees of monogamy, presumably differing based on environment, ease of rearing offspring, proximity of the mating pair etc. As you note, it is not an either-or: broadly monogamous animals cheat. Some cheat more than others. Humans are not one of the never-know-cheating species. Humans cheat a little more than some other monogamous species, less than others. The precise level varies depending on culture.

If you balk at culture being invoked, recall that the statement “1 out of 6 societies” includes those in which men have more than one wife. Since we agree humans are monogamous with a propensity to cheat, the fact many women have ended up sharing a husband (and being fully aware of the fact) says something about the influence of culture.

“The anatomical point related to correlations in primates, where penis and testes size correlate to sexual practices. If, for example, testes size does not differ due to evolutionary reasons, why /does/ it differ. This is not an evolutionary psychology question – its a pure evolutionary question.”

But it’s a question that Darwin would never in a million years have tried to answer by simply noting correlations and extrapolating! So I don’t think it deserves to be classified as a question in evolutionary theory. Its inductive methodology reveals it to be a question in crappy old inductive evolutionary psychology.

I’m always complaining about the mere noting of correlations to draw inductive conclusions in science. It strikes me as distinctly bad science, and in this context it’s used to make an ideological point about what humans are “really” like. That is an old and bad habit of political thinkers.

For example, Hobbes said that humans were by nature solitary, although hardly any real humans are solitary. Rousseau said we were by nature uncorrupted by civilization, although humans who are “uncorrupted” in that way are mostly ignorant and violent sadists. Engels said we are by nature hunter-gatherers, although hardly any humans are actually hunter-gatherers. Now psychologists are saying we are by nature promiscuous, although hardly any humans are as promiscuous as they say.

We can tell what humans are really like by just opening our eyes and observing what they are really like. Claims made about what humans would be like without the influence of culture are badly misguided, as they suppose culture/nurture works against nature, which it doesn’t. This assumed opposition of nurture and nature is one of the most damning contradictions of evolutionary psychology.

Toucans and pelicans have big beaks, but it would be wrong to conclude that toucans are “really” prodigious eaters of fish, or that they would be were it not for the artificial effects of living in the jungle. To find out what toucan beaks are used for, look at real toucans. To find out why human testes are large, don’t extrapolate from correlations between non-humans, but instead look at their role in real human behaviour. Testes are part of the endocrine system as well as organs for the production of sperm. For all we know, greater human sexual dimorphism might call for the production of more androgens.

“There are varying degrees of monogamy, presumably differing based on environment, ease of rearing offspring, proximity of the mating pair etc. As you note, it is not an either-or: broadly monogamous animals cheat.”

Wait! I think it pretty much has to be either-or as far as entire species are concerned. There has to be a “normal” number of carers for the offspring of any species – if there weren’t, there would be distinct disadvantages in having too few or too many. In most vertebrates it’s none, one or two parents. So the question is: do humans normally need two parents or just one? The answer has to be either “one” or else “two”. In normal circumstances that is either-or.

What is not either-or is the amount of cheating found among individuals of a given species. That is variable, but as a reproductive strategy cheating itself requires monogamy to be established, and for some males to be tricked into providing for offspring that aren’t their own. The tricked males have to act as if they were parents in a bonded pair. And of course that can only happen in species where normal reproduction involves bonded pairs.

“If you balk at culture being invoked, recall that the statement “1 out of 6 societies” includes those in which men have more than one wife.”

This happens in some ostensibly monogamous birds as well as humans, but I think it has to be counted as a special sort of cheating – i.e. as a “parasitic” strategy that only works for reproduction as long as it is does not become the norm. Much the same applies to rape. I’m inclined to think that although such strategies are often reproductively successful, which is why they exist in the first place of course, few individuals adopt them by choice. I’d guess that societies in which many members of either sex are unpaired (as happens with polygamy) are generally unhappy and probably rather unstable.

We are humans… I feel monogamy is a stable way of life, for us and our children. I have no desire to cheat on my mate, and when I mate, my intention is for life.. I know the heartbreak of having lost a mate who I intended to stay with and have life adventures with… we as humans have morals and emotional intelligence, and my EI tells me that I do not need to seek outside of my monogamous relationship for sexual fulfillment.. It is simple, we are humans.. we are not just animals. There are many differences between us and the other apes, as much as there are similarities.. they eat bugs out of each
others hair and swing from tree to tree by their feet… do we do that?? .. yes, we are a type of animal, but our spiritual and emotional intelligence dictates more to us now than does just pure instinct, this is part of our evolution!